Near-Total Ear Avulsion Repaired With Primary Closure and Hyperbaric Oxygen: A Case Series and Review of the Literature.

INTRODUCTION: Near-total ear avulsion is a rare and challenging problem to repair with many techniques described; primary repair is an attractive option but is not always successful. Healing may be augmented with postoperative hyperbaric oxygen therapy (HBOT), but this technique is under-reported, and an ideal regimen is not known. The study objective is to discuss the role of HBOT in the management of ear avulsion by reviewing 2 unique cases. METHODS: Case report and review of the literature. A Pubmed search using the terms ear avulsion and postoperative hyperbaric oxygen was performed. RESULTS: Two pediatric patients presented with near-total avulsion of the auricle after suffering a dog bite. Various management options were discussed including observation, primary repair, post-auricular cartilage banking, graft reconstruction with periauricular tissue or rib cartilage, or microsurgical replantation. The decision was made to perform primary reattachment, followed by adjuvant hyperbaric oxygen therapy (HBOT). The patients achieved favorable esthetic results and continue to maintain the function of the reattached ear. Photo documentation was obtained throughout the process. DISCUSSION: There is no consensus on the management of near-total ear avulsion. Primary repair is ideal from a cosmetic and ease-of-operation standpoint but does not always yield viable tissue. The use of postoperative HBOT is an attractive option that may boost success rates, but the ideal HBOT regimen is unknown. These cases represent a successful application of this innovative technique in a pediatric patient.

Technical Note: Validation of the effectiveness of electric stunning for euthanasia of mature swine (Sus scrofa domesticus).

Electrocution and the use of a penetrating captive bolt gun (PCBG) are both acceptable methods of euthanasia for market weight swine. Research has demonstrated that a PCBG is effective in both growing and mature swine. Given limited to no published research base on electrocution in mature swine, the objectives of the present study were to evaluate the efficacy of a two-stage (head only followed by head to heart, 10 s contact for each) mobile electric stunner (E-STUN, Hubert HAAS TBG 96N) and to assess euthanasia outcomes when comparing E-STUN with the frontal placement of a heavy-duty PCBG (Jarvis, In-line Cylinder Style) when applied to heavy-weight (>200 kg) mature boars and sows. Effectiveness of the E-STUN and PCBG was evaluated first in unconscious anesthetized mature swine (n = 7 boars and sows per treatment; average weight 282 ± 48 kg, n = 28) to reduce the risk of failure in a conscious animal and then in conscious mature swine (n = 3 boars and sows per treatment; average weight 282 ± 63 kg, n = 12). Data from both stages were combined for analyses. Treatment efficacy was defined as any pig that achieved cardiac and respiratory arrest within 10 min after treatment application. A three-point traumatic brain injury score (0 = normal; 1 = some abnormalities; and 2 = grossly abnormal, unrecognizable) was used to evaluate six neuroanatomical structures (cerebral cortex, cerebellum, hypothalamus, thalamus, pons, and brain stem), and the presence of intracranial hemorrhage was also noted. All animals were immediately rendered insensible with E-STUN and PCBG, and no difference was noted between treatments for the detection of corneal reflex following treatment application (P = 0.11). Rhythmic breathing was absent following the administration of either E-STUN or PCBG. When evaluating the time to last heartbeat, there was a significant interaction between sex and treatment. Boars euthanized via E-STUN had a 346.8-s decrease in time to last heartbeat compared with boars euthanized via PCBG (P < 0.001), and females euthanized via E-STUN had a 479.3-s decrease in time to last heartbeat compared with females euthanized via PCBG (P < 0.001). Intracranial hemorrhage was common for both methods, and visible disruption of neural tissue was evident due to the physical nature of the PCBG. This study demonstrated that a mobile E-STUN system is as effective as a heavy-duty PCBG in inducing insensibility and death and shows promise as an alternative method for euthanizing mature pigs on-farm.

Euthanasia is a moral obligation of all individuals working in the swine industry. A majority of acceptable methods have been validated for market weight pigs, while less attention has focused on heavy-weight mature boars and sows. The objectives of the current study were to evaluate the effectiveness of a mobile electric stunner (E-STUN) as a method of humane euthanasia in heavy-weight mature boars and sows and to assess the outcomes when compared with a penetrating captive bolt gun (PCBG) method. The efficacy of the treatment was defined as any pig that achieved cardiac and respiratory arrest within 10 min after treatment application. The amount of traumatic brain injury was evaluated across the brain, and the presence of intracranial hemorrhage was also noted. All animals were immediately rendered insensible, and rhythmic breathing was absent following either treatment application. Boars and sows had a decreased time to last heartbeat with the E-STUN when compared with the PCBG method. Intracranial hemorrhage was common for both methods, and visible disruption of brain tissue was evident due to the physical nature of the PCBG. This study demonstrated that a mobile E-STUN is as effective as a PCBG for humane euthanasia of heavy-weight mature swine.

Validating the effectiveness of alternative euthanasia techniques using penetrating captive bolt guns in mature swine (Sus scrofa domesticus).

Euthanasia of mature swine is challenging. Temporal and behind-the-ear locations are two sites that have been identified as alternatives to the more commonly used frontal placement. In stage one, the effectiveness of two penetrating captive bolt gun styles (cylinder or pistol) was evaluated using frontal, temporal, and behind-the-ear placement in anesthetized mature swine (n = 36; weight: 267 ± 41 kg). For stage one, when evaluating treatment efficacy by sex, the cylinder-style equipment was 100% effective in achieving death when applied to all cranial locations (frontal, temporal, and behind-the-ear) for sows; however, the pistol-style equipment was only 100% effective when applied at the behind-the-ear location for sows. For boars, the cylinder-style equipment was 100% effective when applied to the frontal and behind-the-ear location, but the pistol-style equipment was not effective for any cranial location in boars. Therefore, the pistol-frontal, pistol-temporal, pistol-behind-the-ear, and cylinder-temporal were not included for boars, and pistol-frontal and pistol-temporal were not included for sows in stage two. In stage two, commercial, mixed-breed, mature swine (n = 42; weight: 292 +/- 56 kg) were randomly assigned to one of four treatments based on the inclusion criteria described in stage one. A three-point traumatic brain injury (TBI) score (0 = normal; 1 = some abnormalities; 2 = grossly abnormal, unrecognizable) was used to evaluate six neuroanatomical structures (cerebral cortex, cerebellum, hypothalamus, thalamus, pons, and brain stem), and the presence of hemorrhage was also noted. All treatments were 100% effective in stage two. A significant interaction between gun style and placement was determined on predicting total TBI as the cylinder style produced a higher total TBI score compared with the pistol type of the magnitude of +2.8 (P < 0.01). The cylinder style tended to produce a greater TBI score than the pistol in the temporal location (+1.2; P = 0.08). No difference was noted for TBI score behind-the-ear between the cylinder- and pistol-style gun (P > 0.05). TBI tended to be less in boars compared with sows (-0.6; P = 0.08). Hemorrhage was observed in frontal, parietal, occipital, and temporal lobes. This study demonstrated that the cylinder-style captive bolt gun more effectively resulted in brain trauma and death compared with a pistol-style gun and the behind-the-ear and temporal placement showed promise as an alternative placement site for euthanizing mature pigs on-farm.

Identification and Morphogenesis of Vestibular Atrial Septal Defects.

Background: The vestibular atrial septal defect is an interatrial communication located in the antero-inferior portion of the atrial septum. Reflecting either inadequate muscularization of the vestibular spine and mesenchymal cap during development, or excessive apoptosis within the developing antero-inferior septal component, the vestibular defect represents an infrequently recognized true deficiency of the atrial septum. We reviewed necropsy specimens from three separate archives to establish the frequency of such vestibular defects and their associated cardiac findings, providing additional analysis from developing mouse hearts to illustrate their potential morphogenesis. Materials and methods: We analyzed the hearts in the Farouk S. Idriss Cardiac Registry at Ann and Robert H. Lurie Children's Hospital in Chicago, IL, the Van Mierop Archive at the University of Florida in Gainesville, Florida, and the archive at Johns Hopkins All Children's Heart Institute in St. Petersburg, Florida, identifying all those exhibiting a vestibular atrial septal defect, along with the associated intracardiac malformations. We then assessed potential mechanisms for the existence of such defects, based on the assessment of 450 datasets of developing mouse hearts prepared using the technique of episcopic microscopy. Results: We analyzed a total of 2100 specimens. Of these, 68 (3%) were found to have a vestibular atrial septal defect. Comparable defects were identified in 10 developing mouse embryos sacrificed at embryonic data 15.5, by which stage the antero-inferior component of the atrial septum is usually normally formed. Conclusion: The vestibular defect is a true septal defect located in the muscular antero-inferior rim of the oval fossa. Our retrospective review of autopsied hearts suggests that the defect may be more common than previously thought. Increased awareness of the location of the defect should optimize its future clinical identification. We suggest that the defect exists because of failure, during embryonic development, of union of the components that bind the leading edge of the primary atrial septum to the atrioventricular junctions, either because of inadequate muscularisation or excessive apoptosis.

Transoral robotic excision of laryngocele: Surgical considerations.

BACKGROUND: Transoral robotic surgery (TORS) has emerged as a novel, safe, and feasible procedure for the resection of malignant supraglottic laryngeal cancers. The purpose of this study was to demonstrate the surgical technique with extension of the use of TORS to excise a laryngeal cyst. RESULTS: Laryngeal cyst resection, along with its tract, was accomplished with preservation of both false and true vocal cords. There was no perioperative or early postoperative complications. The patient was extubated immediately after surgery. Oral diet was initiated within 24 hours. No tracheostomy was required. A video demonstration of the surgical technique is included on Head & Neck's website. CONCLUSION: TORS is a safe and feasible procedure for excision of selected laryngeal cysts.

Cognitive Functions in Adult Cochlear Implant Users, Cochlear Implant Candidates, and Normal-Hearing Listeners.

OBJECTIVES: Increasing evidence suggests that hearing loss may be linked to cognitive decline, and that cochlear implantation may lead to improvements in cognition. The goal of this study was to examine the effects of severe-to-profound hearing loss and cochlear implantation in post-lingually deafened adults, compared with age-matched normal-hearing (NH) peers. Participants were tested on several non-auditory measures of cognition: working memory (WM) (digit span, object span, symbol span), non-verbal reasoning (Raven's progressive matrices), information-processing speed and inhibitory control (Stroop test), speed of phonological and lexical access (Test of Word Reading Efficiency), and verbal learning and memory (California Verbal Learning Test). Demographic measures were also collected. METHODS: Cohort study at tertiary neurotology center. Forty-three post-lingually deafened experienced CI users, 19 post-lingually deafened CI candidates, and 40 age-matched NH controls with no cognitive impairment were enrolled. Comparisons among the groups on the cognitive measures were performed. RESULTS: Adult CI users and CI candidates demonstrated worse (or a trend towards worse) performance as compared with NH peers on non-verbal reasoning, information-processing speed, speed of lexical access, and verbal learning and memory. However, after controlling for gender, socioeconomic status (SES), and vocabulary knowledge among groups, some of these differences were no longer significant. Similarly, large differences were not found in most cognitive abilities between experienced CI users and CI candidates. CONCLUSIONS: Adult CI users, CI candidates, and NH peers generally demonstrated equivalent non-auditory cognitive abilities, after controlling for gender, SES, and vocabulary knowledge. These findings provide support for a link between cognitive decline and hearing loss, but this association may be partly attributable to group differences in SES and vocabulary knowledge. LEVEL OF EVIDENCE: 2b.

Is the Program-Specific Paragraph Responsible for Declining Application Numbers? A Commentary.

An alarming trend of declining applications to otolaryngology-head and neck surgery has surfaced over the past 3 years. There are many possible explanations for this decline, and a recent publication has implicated "impossible" qualifications as the reason for this decline. While these qualifications may deter a significant number of potential applicants, they have not changed significantly in the past 5 years and do not seem to explain a sudden decline. This commentary argues that the program-specific paragraph, which was introduced in 2015, may be at least in part responsible.

Does treatment of paradoxical vocal fold movement disorder decrease asthma medication use?

OBJECTIVES/HYPOTHESIS: To determine whether diagnosis and treatment of paradoxical vocal fold movement disorder (PVFMD) leads to decreased asthma medication use. Secondary objectives include determining initial rate of asthma medication use, characterizing symptom improvement, and correlating with pulmonary function testing (PFT). STUDY DESIGN: Prospective observational study. METHODS: Patients newly diagnosed with PVFMD at a single institution were recruited to participate. Medication questionnaires were completed at the initial visit, at the first return visit for therapy, and at 6 months. PFTs were reviewed when available. RESULTS: Sixty-six patients were recruited; the study was closed early because findings reached significance. Fifty-six patients (85%) were taking asthma medication at presentation. Forty-four patients presented with PFTs, and two-thirds were normal. Forty-two patients completed follow-up questionnaires; 79% decreased asthma medication use (P < .001), and 82% reported symptom improvement. Seventy-seven percent of patients participated in therapy and 23% did not, with equal rates of decrease in asthma medication use between these groups. Outcomes did not vary based on PFT pattern (i.e., obstructive vs. nonobstructive, P = .75). CONCLUSIONS: Diagnosis and treatment of PVFMD lead to a decline in asthma medication use. This decrease occurred alongside symptom improvement and irrespective of PFT findings. Use of asthma medication in this patient population is high, at 85%. LEVEL OF EVIDENCE: 4. Laryngoscope, 127:1531-1537, 2017.

Pneumobilia Resulting From Choledochoduodenal Fistula Secondary to Metastatic Colon Adenocarcinoma.

Pneumobilia, or air within the biliary tree, is a poor prognostic indicator in a patient without prior biliary sphincterotomy. Differential diagnosis includes infection with gas-forming organisms, choledochoenteric fistula in the setting of gallstones or penetrating ulcer disease, malignant invasion from a primary liver or biliary tract tumor, or metastatic disease. Treatment depends on etiology and patient factors, but often requires surgical intervention. We report a patient with gastrointestinal bleeding in whom pneumobilia was incidentally noted on abdominal plain film. Computed tomography and endoscopy revealed the biliary-enteric fistula to be caused by metastatic colon adenocarcinoma invading the biliary tree.

Biomechanical evaluation contribution of the acetabular labrum to hip stability.

PURPOSE: Knowledge of the effect of hip pathologies on hip biomechanics is important to the understanding of the development of osteoarthritis, and the contribution of the labrum to hip joint stability has had limited study. The purpose of this study was to evaluate the effect of labral injury to stability of the femoral head in the acetabular socket. METHODS: Ten cadaver hip specimens were tested using a robotic system under four different loading conditions: axial loading (80 N) along the femoral axis and axial loading (80 N) combined with either anterior, posterior or lateral loading (60 N). The hip states were examined were intact, with a 1.5 cm capsulotomy and with a 1 cm resection of the anterosuperior labrum. RESULTS: At 30° of flexion, under axial load, the displacement of the hip with capsulotomy and labral resection (9.6 ± 2.5 mm) was significantly larger then the hip with capsulotomy alone (5.6 ± 4.1 mm, p = 0.005) and the intact hip (5.2 ± 3.8 mm, p = 0.005). Also, at 30° of flexion, the displacement under combined axial and anterior/posterior load was increased with capsulotomy and labral resection. CONCLUSION: The acetabular labrum provides stability to the hip joint in response to a distraction force and combined distraction and translation forces. One centimetre of labral resection caused significant displacement ("wobbling" effect) of the femoral head within the acetabulum with normal range of motion. Successful labral repair could be crucial for restoration of the hip biomechanics and prevention of coxarthrosis.

Prophylactic versus reactive PEG tube placement in head and neck cancer.

OBJECTIVE: To understand the impact of percutaneous endoscopic gastrostomy (PEG) tube placement timing on tube duration, weight loss, and disease control in patients with head and neck cancer (HNC). SETTING: A tertiary academic center. STUDY DESIGN: Historical cohort study. SUBJECTS AND METHODS: Seventy-four patients with HNC were reviewed. Patients underwent cisplatinum-based chemoradiation therapy with or without surgical resection. They received a PEG tube either before radiation therapy began (prophylactic) or after (reactive). Patients were matched on the basis of age, gender, TNM stage, tumor subsite, human papillomavirus (HPV) status, and chemoradiation dose. RESULTS: Patients receiving reactive PEG tubes had them in place for fewer days than those placed prophylactically (227 vs 139 days, P < .01). There was no difference in percentage weight loss at 2, 6, or 12 months. There was no difference in survival or disease control between the groups. CONCLUSIONS: Reactive PEG tube placement may afford patients a shorter duration of usage without incurring greater weight loss or poorer oncologic outcomes.

Graft-Versus-Host Disease of the Upper Gastrointestinal Tract After an Autologous Stem Cell Transplant.

Graft-versus-host disease (GVHD) in recipients of autologous stem cell transplantation (SCT) is less common compared to recipients of allogeneic SCT, but its existence has been well documented. Similarly, the diarrheal component of the disease is highlighted when discussing its gastrointestinal (GI) manifestations, with less emphasis given to upper GI symptoms like nausea and vomiting. We present a case illustrating the upper GI tract signs and symptoms of GVHD after autologous SCT, and emphasize that prompt treatment can rapidly improve morbidity and prevent disease progression.

Biomechanical comparison of different graft positions for single-bundle anterior cruciate ligament reconstruction.

PURPOSE: Recent reports have highlighted the importance of an anatomic tunnel placement for anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to compare the effect of different tunnel positions for single-bundle ACL reconstruction on knee biomechanics. METHODS: Sixteen fresh-frozen cadaver knees were used. In one group (n = 8), the following techniques were used for knee surgery: (1) anteromedial (AM) bundle reconstruction (AM-AM), (2) posterolateral (PL) bundle reconstruction (PL-PL) and (3) conventional vertical single-bundle reconstruction (PL-high AM). In the other group (n = 8), anatomic mid-position single-bundle reconstruction (MID-MID) was performed. A robotic/universal force-moment sensor system was used to test the knees. An anterior load of 89 N was applied for anterior tibial translation (ATT) at 0°, 15°, 30° and 60° of knee flexion. Subsequently, a combined rotatory load (5 Nm internal rotation and 7 Nm valgus moment) was applied at 0°, 15°, 30° and 45° of knee flexion. The ATT and in situ forces during the application of the external loads were measured. RESULTS: Compared with the intact ACL, all reconstructed knees had a higher ATT under anterior load at all flexion angles and a lower in situ force during the anterior load at 60° of knee flexion. In the case of combined rotatory loading, the highest ATT was achieved with PL-high AM; the in situ force was most closely restored with MIDMID, and the in situ force was the highest AM-AM at each knee flexion angle. CONCLUSION: Among the techniques, AM-AM afforded the highest in situ force and the least ATT.

Biomechanics of the human triple-bundle anterior cruciate ligament.

PURPOSE: To investigate the biomechanics of the intermediate (IM), anteromedial (AM), and posterolateral (PL) bundles in the human anterior cruciate ligament (ACL). METHODS: Eighteen human cadaveric knees were tested with a robotic/universal force-moment sensor testing system. Anterior tibial translation (ATT) was determined under an 89-N anterior tibial load. Coupled ATT was determined under a combined rotatory load of 7-Nm valgus and 5-Nm internal rotation torque (pivot moment). Each bundle's in situ forces were measured under identical external loading conditions. RESULTS: Under anterior load, the PL bundle's in situ force was highest at 0° and decreased during flexion. Under the anterior load, the AM bundle's in situ force was significantly higher than the IM and PL bundles' force at 15°, 30°, and 60°. Under the pivot moment, the AM bundle's in situ force was significantly higher than the PL and IM bundles' force at 0° and 15°, and the IM bundle had the lowest in situ force at 0° but higher in situ force than the AM and PL bundles at 30° and 45°. IM and AM bundle removal increased ATT under the anterior load at all angles. Cutting the PL bundle after IM and AM bundle removal (whole ACL removal) significantly increased ATT under the anterior load at 0°, 15°, and 30° of knee flexion and increased coupled ATT under the pivot moment at 0° and 15°. CONCLUSIONS: The biomechanical role of each of the 3 ACL bundles (AM, IM, and PL) was measured with a robotic/universal force-moment sensor testing system. The AM bundle stabilized the knee against both the anterior and rotatory loads. The PL bundle stabilized the knee especially near full extension. The IM bundle supported the AM and PL bundles through all flexion angles, especially from 30° to 45°, against the rotatory load. CLINICAL RELEVANCE: Knowledge of functions of the different ACL bundles will help improve ACL reconstruction techniques to enable restoration of normal knee function.

A biomechanical comparison of 2 femoral fixation techniques for anterior cruciate ligament reconstruction in skeletally immature patients: over-the-top fixation versus transphyseal technique.

PURPOSE: The purpose of this study was to compare knee kinematics and in situ forces of the graft between 2 femoral fixation techniques of anterior cruciate ligament (ACL) reconstruction: the over-the-top (OTT) fixation and transphyseal (TP) techniques. METHODS: ACL reconstruction in skeletally immature patients is a challenging procedure. Regarding the femoral fixation techniques, 2 methods are commonly used: the OTT fixation and TP techniques. Ten cadaveric knees (mean age, 57 years; range, 48 to 65 years) were tested with the robotic/universal force-moment sensor system by use of (1) an 89-N anterior tibial load at full extension and 15°, 30°, 60°, and 90° of knee flexion and (2) a combined 7-Nm valgus torque and 5-Nm internal tibial rotation torque at 15° and 30° of knee flexion. RESULTS: Both OTT and TP ACL reconstruction techniques closely restored the intact knee kinematics and had a significant reduction in anterior tibial translation under an anterior tibial load and in coupled anterior tibial translation under a combined rotatory load when compared with an ACL-deficient knee. When both ACL reconstruction techniques were compared, the only difference found was that the in situ force of the ACL graft reconstructed with the OTT technique in response to a combined rotatory load at 30° of flexion was significantly lower than the ACL graft reconstructed with the TP technique (5.3 ± 3.3 N and 10.7 ± 6.0 N, respectively; P = .013). CONCLUSIONS: This time 0 testing showed that both ACL reconstruction techniques, OTT and TP, can reproduce the kinematics of the intact knee in response to an anterior tibial load and a combined rotatory load. CLINICAL RELEVANCE: Both femoral fixation techniques exhibited comparable time 0 kinematics when subjected to simulated clinical examination loading conditions.

Comparison of in situ forces and knee kinematics in anteromedial and high anteromedial bundle augmentation for partially ruptured anterior cruciate ligament.

BACKGROUND: High tunnel placement is common in single- and double-bundle anterior cruciate ligament (ACL) reconstructions. Similar nonanatomic tunnel placement may also occur in ACL augmentation surgery. PURPOSE: In this study, in situ forces and knee kinematics were compared between nonanatomic high anteromedial (AM) and anatomic AM augmentation in a knee with isolated AM bundle injury. STUDY DESIGN: Controlled laboratory study. METHODS: Seven fresh-frozen cadaver knees were used (age, 48 ± 12.5 years). First, intact knee kinematics was tested with a robotic-universal force sensor testing system under 2 loading conditions. An 89-N anterior load was applied, and an anterior tibial translation was measured at knee flexion angles of 0°, 30°, 60°, and 90°. Then, combined rotatory loads of 7-N·m valgus and 5-N·m internal tibial rotation were applied at 15° and 30° of knee flexion angles, which mimic the pivot shift. Afterward, only the AM bundle of the ACL was cut arthroscopically, keeping the posterolateral bundle intact. The knee was again tested using the intact knee kinematics to measure the in situ force of the AM bundle. Then, arthroscopic anatomic AM bundle reconstruction was performed with an allograft, and the knee was tested to give the in situ force of the reconstructed AM bundle. Knee kinematics under the 3 conditions (intact, anatomic AM augmentation, and nonanatomic high AM augmentation) and the in situ force were compared and analyzed. RESULT: The high AM graft had significantly lower in situ force than the intact and anatomic reconstructed AM bundle at 0° of knee flexion (P < .05) and the intact AM bundle at 30° of knee flexion under anterior tibial loading. There were no differences between anatomic graft and intact AM bundle. The high AM graft also had a significantly lower in situ force than the intact and anatomic reconstructed AM with simulated pivot-shift loading at 15° and 30° of flexion (P < .05). Under anterior tibial and rotatory loading, there was a difference in tibial displacement between anatomic and high AM reconstructions and between the high AM graft and intact ACL under rotational loading with the knee at 15° of flexion. CLINICAL RELEVANCE: Anatomic AM augmentation can lead to biomechanical advantages at time zero when compared with the nonanatomic (high AM) augmentation. Anatomic AM augmentation better restores the knee kinematics to the intact ACL state.

Optical coherence tomography detection of subclinical traumatic cartilage injury.

OBJECTIVES: Posttraumatic arthritis is a major cause of disability. Current clinical imaging modalities are unable to reliably evaluate articular cartilage damage before surface breakdown, when potentially reversible changes are occurring. Optical coherence tomography (OCT) is a nondestructive imaging technology that can detect degenerative changes in articular cartilage with an intact surface. This study tests the hypothesis that OCT detects acute articular cartilage injury after impact at energy levels resulting in chondrocyte death and microstructural changes, but insufficient to produce macroscopic surface damage. METHODS: Bovine osteochondral cores underwent OCT imaging and were divided into a control with no impact or were subjected to low (0.175 J) or moderate (0.35 J) energy impact. Cores were reimaged with OCT after impact and the OCT signal intensity quantified. A ratio of the superficial to deep layer intensities was calculated and compared before and after impact. Chondrocyte viability was determined 1 day after impact followed by histology and polarized microscopy. RESULTS: Macroscopic changes to the articular surface were not observed after low and moderate impact. The OCT signal intensity ratio demonstrated a 27% increase (P = 0.006) after low impact and a 38% increase (P = 0.001) after moderate impact. Cell death increased by 150% (P < 0.001) and 200% (P < 0.001) after low and moderate energy impacts, respectively. When compared with unimpacted controls, both Mankin histology and David-Vaudey polarized microscopy scores increased (P = 0.036 and P = 0.002, respectively) after moderate energy impact. CONCLUSIONS: This study shows that OCT detects acute cartilage changes after impact injury at levels insufficient to cause visible damage to the articular surface but sufficient to cause chondrocyte death and microscopic matrix damage. This finding supports the use of OCT to detect microstructural subsurface cartilage damage that is poorly visualized with conventional imaging.

Contribution of the meniscofemoral ligament as a restraint to the posterior tibial translation in a porcine knee.

The meniscofemoral ligament (MFL) is a major structure in the posterior aspect of the porcine knee together with the posterior cruciate ligament (PCL). While the porcine knee is a frequently used animal model for biomechanical evaluation of PCL reconstruction techniques, the contribution of the MFL to stability of the porcine knee is not well understood. The purpose of this study is (1) to evaluate the kinematics of the knee after sequential cutting of the PCL and MFL and (2) to determine the in situ forces of the PCL and MFL in response to a posterior tibial load of 89 N using the robotic/universal force-moment sensor system from 15 degrees to 90 degrees of knee flexion. Ten porcine knees were used in this study. The magnitude of posterior tibial translation under a posterior tibial load was significantly increased (P < 0.01) after sequential transection of the PCL and the MFL at each testing angle compared to the intact condition. The in situ force of the PCL was highest at 60 degrees of flexion (82.3 +/- 8.6 N) and lowest at 15 degrees of flexion (45.1 +/- 15.9 N). The in situ force of the MFL was highest at 15 degrees of flexion (24.3 +/- 6.5 N) and lowest at 90 degrees of flexion (12.9 +/- 10.5 N). The findings in this study revealed a biomechanical contribution of the MFL as the secondary restraint to the posterior tibial translation in conjunction with the PCL especially near full extension.